body {
    height: 100%;
    background-image: url('../image/a.png');
  }
  .form-register {
    width: 100%;
    max-width: 400px;
    padding: 15px;
    margin: 0 auto;
  }
  .form-group {
    margin-bottom: 5px;
  }
  form a{
    display: inline-block;
    margin-top:25px;
    line-height: 10px;
  }